Systematic review with meta-analysis: effect of fibre supplementation on chronic idiopathic constipation in adults

Aliment Pharmacol Ther. 2016 Jul;44(2):103-16. doi: 10.1111/apt.13662. Epub 2016 May 12.


Background: Chronic idiopathic constipation is a common symptom-based gastrointestinal disorder responsible for a substantial economic health service burden. Current guidelines recommend the use of fibre as a first-line treatment.

Aim: To investigate the effect of fibre (including prebiotic) supplementation on global symptom response, stool output, gut microbiota composition and adverse events in adults with chronic idiopathic constipation.

Methods: Medline, EmBase, Web of Science, Scopus and the Cochrane central register of controlled trials were searched through to February 2016. Conference proceedings from 2003 to 2015 were hand-searched. There were no language restrictions. Forest plots with 95% CIs were generated using a random-effects model.

Results: The search strategy generated 1072 citations, of which seven individual randomised controlled trials were eligible. Overall, 113 of 147 (77%) patients assigned to fibre responded to therapy, compared with 61 of 140 (44%) allocated to placebo (RR of success to respond 1.71, 95% CI 1.20-2.42, P = 0.003). Fibre significantly increased stool frequency (SMD, standardised mean difference = 0.39; 95% CI 0.03-0.76; P = 0.03) and softened stool consistency (SMD = 0.35; 95% CI 0.04-0.65; P = 0.02) compared with placebo. Flatulence was significantly higher with fibre compared to placebo (SMD 0.56, 0.12-1.00, P = 0.01). Overall quality of evidence was low.

Conclusions: This meta-analysis demonstrates that fibre is moderately effective, but also causes moderate gastrointestinal side effects. However, these findings need to be treated with caution due to a high risk of bias. Accordingly, further large, methodologically rigorous trials are required, before any definitive recommendation regarding its risk-benefit profile can be made. PROSPERO registration number CRD42014007005.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Adult
  • Constipation / drug therapy*
  • Dietary Fiber / therapeutic use*
  • Flatulence / epidemiology
  • Humans
  • Laxatives / therapeutic use*
  • Randomized Controlled Trials as Topic


  • Dietary Fiber
  • Laxatives